General Science - Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examinations.
71. In which of the following the sound cannot travel?
[A] Solids
[B] Liquids
[C] Gases
[D] Vacuum
Show Answer
Correct Answer: D [Vacuum]
Notes:
Sound cannot travel in vacuum. Sound is a mechanical wave and needs a material medium like air, water, steel etc. for its propagation.
72. What do we call the magnitude of the maximum disturbance in the medium on either side of the mean value called as?
[A] Frequency
[B] Angular Displacement
[C] Amplitude
[D] Wave number
Show Answer
Correct Answer: C [Amplitude]
Notes:
The magnitude of the maximum disturbance in the medium on either side of the mean value is called the amplitude of the wave. It is usually represented by the letter A.
73. Which of the following are generally used to reduce reverberation in an auditorium as sound absorbents?
[A] compressed fibreboard
[B] rough plaster
[C] draperies
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
To reduce reverberation, the roof and walls of the auditorium are generally covered with sound-absorbent materials like compressed fibreboard, rough plaster or draperies.
74. What is the effect on apparent frequency when the distance between the source of the sound and listener is decreased?
[A] it increases
[B] it decreases
[C] it remains same
[D] None of the above
Show Answer
Correct Answer: A [it increases]
Notes:
As per the Doppler effect, when the distance between the source and listener is decreasing the apparent frequency increases. It means the apparent frequency is more than the actual frequency of sound.
75. Which of the following is another unit of frequency?
[A] decibel
[B] cycle per second
[C] metre per second
[D] second
Show Answer
Correct Answer: B [cycle per second]
Notes:
The change in density from the maximum value to the minimum value, again to the maximum value, makes one complete oscillation. The number of oscillations per unit time is the frequency of the sound wave.
76. Which of the following represents the relationship between the Fahrenheit temperature and Celsius temperature?
[A] tf = (tc x 180)/100 – 32
[B] tf = (tc x 100)/180 – 32
[C] tf = (tc x 100)/180 + 32
[D] tf = (tc x 180)/100 + 32
Show Answer
Correct Answer: D [tf = (tc x 180)/100 + 32]
Notes:
A relationship for converting between the two scales may be obtained as: tf = (tc x 180)/100 + 32
77. What is the triple point of water?
[A] Temperature = -273.16 K, pressure= 6.11×10-6Pa
[B] Temperature = -273.16 K, pressure= 6.11×10-3 Pa
[C] Temperature = 273.16 K, pressure= 6.11×10-6 Pa
[D] Temperature = 273.16 K, pressure= 6.11×10-3 Pa
Show Answer
Correct Answer: D [Temperature = 273.16 K, pressure= 6.11×10-3 Pa]
Notes:
The triple point of water is represented by the temperature 273.16 K and pressure 6.11×10-3 Pa.
78. Which of the following law states that if two systems are in thermal equilibrium with a third system separately, then they are in thermal equilibrium with each other?
[A] First law of Thermodynamics
[B] Zeroth law of Thermodynamics
[C] Second law of Thermodynamics
[D] Third law of Thermodynamics
Show Answer
Correct Answer: B [Zeroth law of Thermodynamics]
Notes:
Zeroth Law of Thermodynamics states that ‘two systems in thermal equilibrium with a third system separately are in thermal equilibrium with each other’.
79. Which of the following represents the Snell’s law?
[A] sine of angle of incidence/sine of angle of refraction = constant
[B] cosine of angle of incidence/cosine of angle of refraction = constant
[C] tangent of angle of incidence/tangent of angle of refraction = constant
[D] angle of incidence – angle of refraction = constant
Show Answer
Correct Answer: A [sine of angle of incidence/sine of angle of refraction = constant]
Notes:
The ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media. This law is also known as Snell’s law of refraction.
80. Which of the following gives the power of a lens?
[A] equal to its focal length
[B] reciprocal of its focal length
[C] half of its focal length
[D] double the focal length
Show Answer
Correct Answer: B [reciprocal of its focal length]
Notes:
The power of a lens is defined as the reciprocal of its focal length.
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